Alternating-current signaling system



R. D. PARKER AND B. P. HAMILTON.

ALTERNATING CURRENT SIGNALING SYSTEM.

APPLICATION FILED JUNE 26, I918.

Patented July 5, 1921.

2 SHEETS-SHEET 1.

. Q EGBSQ wawmmmm an w INVENTORS- RD Parker isBPHamiltm BY 5. fi e/z ATTORNEY R. D. PARKER AND B. P. HAMILTON.

ALTERNATING CURRENT SIGNALING SYSTEM. APPLICATION FILED JUNE 26, 1918.

1,383,750., Patented July 5, 1921 2 SHEETS-SHEET 2.

ATTORNEY lecting entree RALZETEOND D. PARKER M13 u Bil-SKELETON, 0F BROUKLYN, NEW YORK,

ASSIGNOM T0 AMERICAN TELEPHONE MED TELEGRAPH GQMPANY, A COR/P0- RATIGN OF NEW YORK.

ALTERNAJING-CTURBfltT SIGNALDG'G srsrma.

Application filed June 26,

transmitted from a sending to. a receiving station in order to control printing or other translating apparatus.

()ne object of this invention is to obtain a number'of printing or signaling channels froma single circuit, so that the same circuit may be utilized for the transmission of a plurality of messages. Another object is to eliminate the necessity for synchronism between distributers at the ends of the line or circuit. Another object is to provide'a signaling system in which under certain conditions a plurality of signaling channels are successively associated with a common transmission circuit without the use of rotating or other moving distributors. Another object is to provide a signaling system in which a main line may be provided with a number of branches leading to intermediate stations without necess1tating synchronous distrlbuters at intermediate receiving stations. A further object of the invention is to reduce the time intervalnecessary for the transmission of a signal combination. Still another object of the invention is the production of a printing system in which the selection of a character depends upon the transmission of a plurality of frequenc es either simultaneously or successively, instead of upon the transmission of asuccession of impulses of varied characteristics.

The foregoing results are accompllshed, and other objects more fully appearing hereinafter are attained, by impressing upon the sending end of a line circuit a plurality of character selecting frequencies togetherwith a channel selecting frequency, and by providing at the receiving end a channel selecting device responsive to the channel sefrequency or frequencies, together with a plurality of character selecting devices responsive to the character selecting frequencies transmitted, said selecting devices controlling any one of several trans- Specification of Letters Patent.

Patented July 5, 1921.

191a. semi at. aaaoae;

lating arrangements, depending upon the channel selected. By successively transmit ting a plurality of channel selecting frequencies, each accompanied by the corresponding character selecting frequencies, the various channels are successively selected at the receiving station and the character selecting devices will respond to the character select ing frequencies to successively control the translating devices of a plurality of receiving channels. With such an arrangement it is also possible to provide the main line with branches or channels running to intermediate receiving stations provided with channel selecting devices, thereby eliminating the use of synchronized distributers at uch stations. By simultaneously applying the several elements of a code combination to the line instead of transmitting them successively the time period necessary for the transmission of each character or signal may also be reduced.

The invention may now be more fully understood from the following description when readin connection with the accompanying drawings, Figure 1 of which constitutes a circuit diagram of a. preferred form of transmitting arrangement, and Fig. 2 of which is a circuit diagram of a preferred form of receiving arrangement employed.

Referring to the drawings, the transmitting arrangement. shown in Fig. 1 is connected to a line L extending to a distant station at which the receiving arrangement illustrated in Fig. 2 is located. The line L is duplexed in the usual manner, so that signals transmitted from the transmitting ar' rangement at one station will not affect the receiving apparatus at that station, the line L being balanced at the station of Fig. 1 by a network X, and being balanced atthe station of Fig. 2 by a network X At the transmitting station a distributer, preferably of the'rotating type, is employed, said distributor having segments S S and $5,, each segment corresponding to one of four signaling channels to be hereinafter described. The distributer is also provided with segments D D D and D for the purpose of controlling local circuits associated with the transmitting channels. A. brush B of the distributor is connected to the line L and a brush B is connected to a local circuit, said brushes being adapted to rotate successively over segments, 8, to S inclusive and D to D, inclusive, respectively.

Transmitters T T,, T, and T are provided for the four signaling channels. These transmitters may be of any well known type and may be either tape actuated characteristic of a particular channel, the

function of these sources being to select or render operative the'corresponding channel at the other end of the line. A series of alternating current sources G G G G, and is also provided for signaling purposes, each source having a different frequency, so that when any combination of signaling frequencies is applied to the line, together with a channel selecting frequency, receiving devices atthe distant station and corresponding to the channel responsive to the channel selectingfrequency, will be operated. I

In order to apply the proper combination of frequencies to the line, four sets of live relays are provided, one set corresponding to each transmitting channel. Thus relays 16, 26, 36, 4:6 and 56 correspond to the channel associated with segment S relay 16 being adgpted to connect alternating current source T to the segment S relay 26 being adapted to connect the alternating current source G to the segment S and so forth, Similarly relays 17, 27, 37, 47 and 57 correspond to the channel associated with segment 3,, relays 18, 28, 38, 4:8 and 58 correspond to the channel associated with seg ment S and relays 19, 29, 39, 49 and 59 1 correspond to the channel associated with segment S Relays 19, 29, 39,49 and 59., corresponding to the channel associated with segment 8,, have one terminal of each of their windings connected to the segment ll) of the distributer. The other terminals of the windings areconnected to the pin contacts P P P and P of the transmitter T In a similar manner the other'sets of relays areconnected to the segments D D and D of the distributer and to .the pin contacts of the transmitters T T and T The pin contacts of these three transmitters and the corresponding connections to the relays are omitted in order to avoid complicatingthe diagram, but it will be understood that t e connections are similar to those described in connection with relays 19, 29, 39, 49, and 59.

-work X Upon actuating any transmitter,

however, such as the transmitter T certain of the contacts of the transmitter will be closed, and whenthe brush B of the distributer passes over the proper segment such as D certain of the relays such as 19, 29, 39, 4:9 and 59, corresponding to the actuated contacts of the transmitter, will be ener' gized to disconnect the corresponding inductances from the channel and substitute therefor a corresponding combination of the generators G to G inclusive. Consequently when the brush B passes over the corresponding channel segment such as S,,,

a plurality of alternating currents from a combination ot the generators G to G inclusive and a generator such as G, corresponding to the channel, will be impressed upon the line.

The brushes B and B are so1 arranged with respect to the corresponding channel" and local segmentsof the distributer that the brush B makes contact with the local segment before the brush B ;makes contact with the corresponding channel segment.

This is for the purpose of energizing the signal controlling relays of the generators before the channel is associated with the line a to avoid the transient effects which would be produced by the opening and closing of the line due to the operation of any signal con trolling relays after the brush B makes con tact with the channel segment. The combination of frequencies from generators G to G inclusive is on the line until the brush B opens the circuit of the signaling relays of the channel upon leavin the corresponding local segment. Brush then disconnects" the line from the channel segments before the signal controlling relays can close the line again through their back contacts and the impedances associated with each relay to avoid transient effects similar to those mentioned above. By this arrangement the transmitters T T 'T and T may be operated either simultaneously or in any order, without any interference of signals,as the combination of frequencies determined by the actuation of any transmitter is not impressed upon the line until the brushes of the distributer pass over the segments of the channel corresponding to that transmitter.

At the receiving station shown in Figfl a loop is brid ed across the line in which receiving units T N N and N, are included for selecting the prope r receivingchannel,

' responsive to the frequencies transmitted neeavso ferent frequencies. Thus units N, to N inclusive are selective of the frequencies transmitted over the line from alternating current sources G to G inclusive, respectively. Similarly, the units N, to N inclusive, are

from the alternating current sources G to G inclusive,respectively.

lhe receiving apparatus is further provided with a plurality of selective relays.

divided into four groups or sets of five re lays each,each set of relays corresponding to one receiving channel. Thus relays R R 11, R and R are associated with the first receiving channel which corresponds to the transmitting channel associated with the distributer segment S In a similar manner relays R to R are associated with the second receiving channel, relays R to R inclusive, are associated with the third receiving channel and relays R to R inclusive, are associated with the fourth receiving channel. Each set of relays is adapted to be selectively operated to control a receiving printer unit which may be of any well known type and as it forms no part of the present invention, is not illustrated.

In order to determine which set of selective relays is to be operated, relays R R,, R, and R, are provided, these relays being associated with the tuned receiving units N N N and N, preferably through transformersn" Relays R to R inclusive, may be direct current relays associated with the receiving units N to N inclusive, through detectors, orthey may be alternating current relays connected with the corresponding receiving units either directly through a transformer'or indirectly through an amplifier. In order to simplify the diagram the connection for the relay B, only is shown, this relay being included in the output circuit of a vacuum tube amplifier A, of well known type, the input or grid circuit of which is inductively associated with the tuned receiving unit N,,. It will be understood, 2 however, that the remaining relays R R and R, will be connected in the same.

way as the relay R In order to determine which selector re; lays of a given set are to be operated, relays R,, R R,, R, and R, are provided. These relays, like the relays R 'to R inclusive, may be either direct or alternating currentrelays, but, as indicated in the case of the relay R these relays are associated. with the output circuits of vacuum tube amplifiers, such as A the input or grid circuits of which are coupled through transformers to the corresponding tuned receiving units, such as N,'.

By means of this arrangement when a combination of frequencies, consisting of a plurality of selecting frequencies upon which is superposed a channel determining frequency, is transmitted over the line L, one of the relays R to E inclusive, corre sponding to the channel determining frequency, is actuated to connect one pole of the battery 2 to the corresponding set of selector relays, while certain of the relays R1 to R inclusive, corresponding to the selecting frequencies are operated to connect the other terminal of the battery to individual relays of the set. {As the brush B of the distributer at the transmitting station rotates over the channel segments S to S inclusive, the channel selecting relays R to R inclusive, are operated successively.

Relays R R and R, have their contacts so arranged that upon the operation of any one of these relays the circuit completed from one terminal of the battery 2 to the previously selected set of selector relays will be opened; This arrangement is provided for the purpose of avoiding the interference which would occur if the preceding channel selecting relay should happen to be slow in releasing. v'llhe relay R which is always operated just after the relay R has its contacts so arranged as to short circuit the relay B, so as to insure that said relay will be de-' energized immediately to open the circuit relays and complete the connection from the battery 2 over the several channel selector relays in series to the first set of selector relays.

T he apparatus employed in connection with the invention will now be fully under.-

stood from a description of the operation.

Assuming that the transmitter T, is actuated, thereby closing its contacts P P and P to determine the character to be printed,

19, 39 and 59,'andover the contacts P P and P to the negative terminal of the battery. Relays 19, 39,and 59 are thereby energized to disconnect the corresponding impedance coils from the fourth transmitting channel and connect the alternating current sources G G and G, to said channel over the front contacts of said relays. As soon previously closed for the last set ofselector after the energization of the relays 19, 39

and 59, the fourth channel is connected to the line L over the following circuit:

From line L, over the brush B, segment 8,, alternating current source G upper front contact of relay 19, alternating current source G lower front contact of relay 19, upper back contact of relay 29, through the impedance coil controlled by relay 29, lower back contact of relay 29, upper front contact of relay 39, al-

ternating current source G lower front contact of relay 39, upper back contact of relay 49, through the impedance coil correspondingtorelayttl, lower back contact of relay 49, upper front contact of relay 59, alternating current source G lower front contact of relay 59 to the network X A plurality of frequencies corresponding to alternating current. sources G G G and G are now transmitted over the line lh tothe receiving arrangement shown in Fig, 2. The tuned receiving unit N,, which is selective of the frequency generated by the alternating current source G selects this frequency and transmits itthrough an aimplifier (not shown), to the alternating current relay R which is energized to discon, nect the positive terminal of the battery 9 from the third set of selector relays if it had not beenalready disconnected therefrom by the deenergization of the relay R and connect said terminal of the battery over the front contact of relay R, to the fourth set of selector relays. t the same time tuned receiving units N and N which are selective of the, frequencies generated by alternating current sources, G G, and G transmit said frequencies to the alternating current relays lt lit, and R through amplifiers (not shown).' Relays R R and R are energized and connect the negative terminal of battery 2, to selector relays 19, 39, and 59. These three selector rclays are nowioperated and control the selection of a character to be printed understood manner.

As soon as the brush B of the transmitting distributer leaves the segment lD the relays 19, 39, and 59are deenergized to disconnect the correspoiiding alternating current sources from the fourth transmitting channel, and the brush passes to the segment D to close a circuit of a combination of the relays 16 to 56, inclusive, determined by the transmitter T The brush B as it passes from the segment S, disconnects the fourth transmitting channel from the line and the brush passes on to the segment S, to connect the first transmitting channel to the line, As soon as the brush leaves the segment S,, the combination of frequencies which had been impressed upon line in response in a well to the actuation of-the transmitter T no longer actuates the alternating current re-- lays lit- R lit, and R and these relays are restored to normal with the consequent de energization of selector relays R R and.

lit will be understood that any convenient frequency range may. be used withthis system so long as the frequencies are sufiiciently far apart to avoid interference and so long as the lower limit of the range is not solow as to reduce the working speed materially.

It will be further understood that the genchannels with said transmission circuit, cor,

responding channels at the receiving station permanently associated with said transmission circuit, and means at the sending station to transmit currents having different characteristics for each channel as successive channels are associated with the transmission circuit and means at the receiving station responsive to said currents to select the corresponding receiving channels. 6

2. in a signaling system, a sending sta= tion, a receiving station, a transmission circuit interconnecting said stations, a plurality of signaling channels at said sending station, means to successively associate said channels with said transmission circuit, means to associate with said transmission circuit currents of frequencies corresponding to said channels, there being a different frequency for each channel, channels permanently associated with said transmission circuit at the receiving stations and corresponding one to each of said channels at the sending station, and means at the receiving station responsive to the frequency corresponding to each channel at the sending station to select the corresponding channel at the receiving station.

3. In a signaling system, a sending station, a receiving station, a. transmission circuit interconnecting said stations, a plurality of signaling channels at said sending station, a source of current variations associated with each channel for generating currents of different frequencies for each channel, means to successively associate the channels and the corresponding sources with the transmission circuit, a plurality of chain nels permanently associated with the trans mission circuit at the receiving station, one

corresponding to each channel at the sendassay/so ing station, and means responsive to the frequency corresponding to each channel at the sending station to select the corresponding channel at the receiving station.

4. In a signaling system, a sending station, a receiving station, a transmission circuit interconnecting said stations, aplurality of signaling channels at said sending station, a source of channel selecting frequency associated with each channel, means to successively associate said channels with said transmission circuit, means to apply to each channel a combination of character selecting frequencies when it is associated with said transmission circuit, a plurality of sets of character select ing devices at the receiving station, one set corresponding to each channel at the sending station, and means responsive to the channel selecting frequency transmitted 'when a given channel is associated with. the

station, and means at the receiving station responsive to a channel selecting frequency transmitted. at a given time to r'enderthe set of character selecting devices corresponding to the channel selecting frequency transmitted responsive to the combination of character selecting frequencies transmitted simultaneously therewith.

6. In a signaling system a transmission line, aplurality of signaling channels, a source of current individual to each channel', each source having frequency characteristics different from those of the other,

sources, and means to successively associate said channels with said lincto apply current from said sources to the line.

7. In a signaling system, a transmission line, a plurality of signaling channels, a-

plurality of sources of current common to said channels, a source of current individual to each channel, means to successively associate said channels with said line, and means to successively associate said individual source and various combinations of said com.- mon sources with said channels as they are associated with the line.

8. In a signaling system, a transmission line, a plurality of signaling channels, a plurality of sources of current of different frequencies common to said channels, a

source of current individual to each channel, means to successively associate said' channels with said line, and means to successively associate said individual sources and various combinations of said common sources with said channels as they are associated with the line.

9. lln a signaling system, a transmission line, a plurality of signaling channels each having a. channel selecting source of current of characteristic frequency individual there to, a pluralityof sources of current of different frequencies common to said channels, means to successively associate said channels with said line, and means to associate various combinations of said common sources with each channel when it is associated with the. line.

10. ln a signaling system, a transmission line, a plurality of signalingchannels, a plurality of sources of current of different frequencies common to said channels and adapted to be associated with said channels in accordance with various code combinations, :1 source of current individual to each channel, means toesuccessively associate said channels with said line, a plurality of code controlling arrangements, one corresponding to each channel, and means operating as the channels are associated with the line to successively associate said individual sources and common sources with said channel in accordance with code combinations determined by the corresponding code controlling. arrangements.

11. In a signaling system, a transmission. line, a plurality of signaling channels, a p1urality of sources of current of different frequencies common to said channels and adapted to be associated with said channels in accordance withvarious code combinations, means to successively associate said channels with said line, a plurality of code controlling devices one corresponding to each channel, a plurality of sets of relays, one set corresponding to each channel and the relays in each set corresponding to. said current sources, and means operating immediately before a. given channel is associated with the line to operate a combination of the relays of the corresponding set determined by the correspondin code forming device, wherep by a combination of said sources will be associated with the channel. V 12. In a signaling system, a transmission line, a plurality of signalingchannels, a plurality of sources of current of different fre-v quencies common to said channels and adapted to. be associated with said channels in accordance with various code combinations, means to successively associate said channels with said line, a plurality of code controlling devices one corresponding to each channel, a plurality of sets of relays, one set corresponding to each channel and the relays in each set corresponding to said current sources, means whereby when a given channel is associated with the line, a combination of the relays of the corresponding set is operated to associate the current sources with the channel in a combination determined by the corresponding code controlling device, and means to restore said relays before the channel is disconnected from the line.

.13. In a signaling system, a transmission circuit over which a plurality of frequencies may be simultaneously transmitted, a plurality of groups of selecting devices, means associated with said line and responsive to certain frequencies .to select a group of selecting devices and means associated with said line and responsive to other frequencies to operate various combinations of devices of the group selected.

14:. In a signaling system, a transmission circuit over which a plurality of frequencies may be simultaneously transmitted, a plurality of sets of selecting devices, a plurality of relays associated with said line each responsive to a definite frequency, certain of said relays operating to select a set of selecting devices and other of said relays op erating to actuate various combinations of selecting devices of the set selected.

15. In a signaling system, a transmission circuit over which a plurality of frequencies may be simultaneously transmitted, a vplu 1 ralityof sets of translating devices, a plurality of frequency responsivedevices associated with said line. and each responsive to a definite frequency, certain of said frequency responsive devices operating to select a set of translating devices, and others of said frequency responsive devices operating to actuate various combinations of trans.

lating devices of the set.

16. In a signaling system, a transmission circuit over which a plurality of frequencies may -lo'e simultaneously transmitted, a plurality of sets' of selecting devices, a plurality of relays associated with saidline each responsive to a definite frequency, devices. for

amplifying and detect'ng frequencies transmitted from said lin to each relay, certain of said relays operating to select a set of se lectmg devices and other of said relays opcrating to actuate various combinations of selecting devices of the set selected.

17. In a signaling system, a transmission circuit over which a plurality of frequencies may .be simultaneously transmitted, a plurality of sets of selecting devices, a plurality of tuned units in said line, each unit com-' prising a capacity and inductance in parallel,

and each unit being tuned to a definite frequency, frequency responsive means associ-,

ated with each tuned unit, certain of said frequency responsive means operating to select a set of selecting devices and other of said frequency responsive means operating to actuate selecting devices of the set selected. 18. In a signaling system, a transmission line, a plurality of transmitting channels normally disconnected therefrom, a plurality of receiving devices, one corresponding to each transmitting channel and normally unconditioned to receive signals transmitted over said line, and means individual to each receiving device and responsive to the connection of a transmitting channel to the line to condition the corresponding receiving device to receive signals regardless ofwhether or not signals are transmitted from said channel.

, 19. In a signaling system, a transmission line, a plurality of transmitting channels astransmitting channel and normally unconditioned to receive signals transmitted .over the line, means to impress upon the line frequencies' characteristic of each channel, and means responsive to such [frequencies to condition the receiving devices to receive signals regardless of whether-or not signals are transmitted.

21. In a signaling system, a transmission line, a plurality of transmitting channels associated therewith, means associated with eachchannel to impress upon theline a frequency characteristic of the channel and a plurality of signaling frequencies, receiving device's associated with the line one corresponding to each transmitting channel, and I selective means whereby each receiving de- 'vice will respond to. signaling frequencies transmitted from the corresponding transmitting channel only when the frequency characteristic of n that channel isimpressedupon the line. w

In testimony whereof, we have signed our names to this specification this eighteenth ay of June,19l8. 1 RALZEMUND I). PARKER.

BAX'IER' I HAMILTUN. 

